Remote systems, such as vehicles, have been introduced that include locomotion power derived from electricity received from an energy storage device such as a battery. For example, hybrid electric vehicles include on-board chargers that use power from vehicle braking and motors to charge the vehicles. Vehicles that are solely electric generally receive the electricity for charging the batteries from other sources. Battery electric vehicles (electric vehicles) are often proposed to be charged through some type of wired alternating current (AC) such as household or commercial AC supply sources. The wired charging connections require cables or other similar connectors that are physically connected to a power supply. Cables and similar connectors may sometimes be inconvenient or cumbersome and have other drawbacks.
Wireless charging systems that are capable of transferring power in free space (e.g., via a wireless field) to be used to charge electric vehicles may overcome some of the deficiencies of wired charging solutions. As such, wireless charging systems and methods that efficiently and safely transfer power for charging electric vehicles are desirable.
Wireless power transfer systems may utilize inductive power transfer (IPT). In IPT, power is transferred from a base or primary power device to a pick-up or secondary power device. Typically, each device includes one or more windings of electric current conveying media, such as wires, so are commonly referred to as coils. Inductive power devices used for supplying wireless power to electric vehicles may be subject to harsh conditions both in terms of impact and compressive forces and also in terms of exposure to the elements, especially water. This is particularly the case for wireless power transfer systems in which the base power device is positioned on the ground and may frequently be driven over by vehicles. A pick-up coil on the underside of a vehicle may also be subject to impacts from road surfaces and the like. Accordingly, a need exists for wireless power transfer devices that are strong, robust and capable of withstanding the conditions to which they are subjected. It is also generally desirable for a wireless power transfer device to have a structure that provides ease of assembly and an associated reduction in manufacturing complexity and costs.